The present invention relates to an electronic device of a type in which musical tones are generated in accordance with pitches extracted from input waveform signals, and more particularly to an electronic string musical instrument such as an electronic guitar and a guitar sythesizer.
Recently, there have been developed various electronic instruments in which a pitch (a fundamental frequency) is extracted from a human voice or a waveform signal generated in response to a performance operation of a natural or conventional musical instrument, and under control of the extracted pitch, a sound source unit of electronic circuits is driven to artificially generate sounds such as musical tones.
This type of the technique is disclosed in the following documents: U.S. Pat. No. 4,117,757, issued Oct. 3, 1978, Akamatsu; U.S. Pat. No. 4,606,255, issued Aug. 19, 1986, Hayashi et al.; U.S. Pat. No. 4,633,748, issued Jan. 6, 1987, Takashima et al.; U.S. Pat. No. 4,688,464, issued Aug. 25, 1987, Gibson etal.; KOKOKU No. 57-37074, examined publication Aug. 7, 1982, Applicant ROLAND KABUSHIKI KAISHA; KOKOKU No. 57-58672, examined publication Dec. 10, 1982, Applicant ROLAND KABUSHIKI KAISHA; KOKAI No. 55-55398 published Apr. 23, 1980, Applicant TOSHIBA KABUSHIKI KAISHA; KOKAI No. 55-87196, published July 1, 1980, Applicant NIPPON GAKKI SEIZO KABUSHIKI KAISHA; KOKAI No. 55-159495, published Dec. 11, 1980, Applicant NIPPON GAKKI SEIZO KABUSHIKI KAISHA; KOKAI (Utility Model) No. 55-152597, published Nov. 4, 1980, Applicant NIPPON GAKKI SEIZO KABUSHIKI KAISHA; KOKAI (Utility Model) No. 55-162132, published Nov. 20, 1980, Applicant KEIOU KIGGEN KOUGYO KABUSHIKI KAISHA; KOKOKU No. 61-51793, examined publication Nov. 10, 1986, Applicant NIPPON GAKKI SEIZO KABUSHIKI KAISHA; KOKOKU (Utility Model) No. 62-20871, examined publication May 27, 1987, Applicant FUJI ROLAND KABUSHIKI KAISHA.
Further, Uchiyama et al. filed on Oct. 22, 1987 a U.S. Pat. Application Ser. No. 112,780 which discloses a system relating to the present electronic device.
In the prior arts disclosed in the above identified documents, a frequency of a musical tone generated from a sound source is varied, in general, in accordance with a pitch of human voice or a vibration signal, which pitch varies with respect to time.
For instance, in the guitar sythesizer, the string tension if varied by a manipulation of the tremolo arm, whereby the frequency of the string vibration changes. Or a choking manipulation increases the frequency of the string vibration. It is required that the frequency of the musical tone to be generated from the sound source varies in accordance with such pitch variations. Various improvements have been made in conventional systems to fulfill such requirements.
In the conventional systems, emphasis has been placed only on the effect that the frequency of the musical tone faithfully follows the variations in the pitch. Accordingly, for example, there has been caused such a problem that the musical tone to be generated follows fine variations in the string vibration with an excess sensitiveness so that it produces frequency variations which are harsh to the ear.